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General Engineering Science Fair Project

Mariotte Siphon for Constant Flow

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Mariotte Siphon for Constant Flow | Science Fair Projects | STEM Projects
You might expect water to flow faster from a full container than a nearly empty one. A Mariotte siphon proves that wrong with a sealed vent tube. Drill a hole in the cap of a 2-liter bottle. Thread a tube through the cap so it reaches partway down. Cut an outlet hole near the base and insert a short straw. Fill the bottle and seal the cap. The vent tube sets the pressure at the outlet. The flow rate stays the same whether the bottle is full or nearly empty. Farmers use this principle to apply fertilizer evenly across a field.

Hypothesis

The hypothesis is that the Mariotte Siphon will apply fertilizers to a field in a constant and uniform manner.

Method & Materials

You will peel the label off of a 2-liter bottle, cut a small hole in the side of the bottle, seal the edges around the straw with Shoe Goo, drill a hole in the cap of the bottle, fill the bottle with water, and measure the flow rate of the siphon.
You will need a 2-liter bottle with cap, an exacto knife, a small drill, Shoe Goo, a small round tube about 2 inches long, a plastic tube from a Windex bottle, a stop watch, and a graduated cylinder.

Results

This project demonstrates how to construct a Mariotte Siphon, a device that will apply fertilizers to a field in a constant and uniform manner. The flow rate of the siphon can be measured and the shape of the jet of water exiting the siphon can be observed. This device is useful for applying liquid fertilizer to field crops in a uniform manner, reducing the chance of overfertilizing and contaminating the groundwater.

Why do this project?

This science project is unique because it teaches students how to construct a device that can be used to apply fertilizers to a field in a consistent and uniform manner.

Also Consider

Experiment variations to consider include measuring the flow rate of the siphon with different vent tubes and observing the shape of the jet of water exiting the siphon when the vent tube is removed.

Full project details

Additional information and source material for this project are available below.

Related video

These videos explain the science behind this project and demonstrate key concepts used in the experiment.
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